JP2004098934A - Motorcycle tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the performance of absorbing shock/vibration from a road surface while securing high turning force during turning. <P>SOLUTION: This motorcycle tire comprises one belt layer consisting of cords arrayed approximately parallel in the peripheral direction. The belt layer has an arcuate portion protruded inside in the radial direction and arranged between two arcuate portions both protruded outside in the radial direction in the cross section of a tire equator. <P>COPYRIGHT: (C)2004,JPO

Description

【００２９】
表１において、点Ｐの幅方向位置は、ベルト層８の、半径方向内側に凸となる円弧状部分の中心の、幅方向位置ｗを、前述の通り定義した（ｗ／ＴＷ）で表わした数字である。表１から明らかなように、ベルト層に半径方向内側に凸となる円弧状部分Ａ１を配設しない場合や、円弧状部分Ａ１を配設したとしてもその幅方向位置が式（１）で示す範囲にない場合には、旋回性能並びに吸収性能を向上させることができない。
【００３０】
【発明の効果】
以上述べたところから明らかなように、本発明によれば、周方向にほぼ平行に配列されたコードよりなりベルト層は、タイヤ子午線断面において、ともに半径方向外側に凸となる円弧状部分Ａ２、Ａ３の間に、半径方向内側に凸となる円弧状部分Ａ１を配設しているので、旋回時の高い旋回力を確保するとともに路面からの衝撃・振動に対する吸収性能を向上させることができる。
【図面の簡単な説明】
【図１】本発明に係る二輪車用タイヤの子午線断面図である。
【図２】図１の部分拡大図である。
【符号の説明】
１　二輪車用タイヤ
２　トレッド部
３　サイドウォール部
４　ビード部
５　ビードコア
７　カーカス
８　ベルト層
９　ベルト
１１　間ゴム
Ａ１〜Ａ３　ベルト層の円弧状部分
Ａ４　カーカスの円弧状部分
Ｐ　ベルト層の円弧状部分Ａ１の中心
Ｋ　ベルト層の幅方向端[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tire for a motorcycle, and more particularly to a tire for a motorcycle having a belt layer made of cords arranged substantially parallel to a circumferential direction and capable of running stably during high-speed turning.
[0002]
[Prior art]
With the increase in the speed of motorcycles, tires having a belt layer made of cords arranged substantially parallel to the circumferential direction have come to be used, but this tire suppresses the growth of the tire diameter at high speeds. Although there is an advantage that durability can be improved and impact can be well absorbed due to low bending stiffness, there has been a problem that the turning force of the motorcycle is insufficient due to low lateral stiffness of the tire.
[0003]
As a countermeasure against this problem, a tire in which a breaker is disposed radially inward of the belt layer or a tire in which hard rubber is disposed from a radially outer portion of a sidewall to an end of the belt layer (for example, see Patent Document 1) 1)) has been proposed or implemented, but any of the tires can increase the lateral rigidity. However, due to the increase in the lateral rigidity, the impact and vibration due to the unevenness of the road surface are absorbed when the motorcycle turns. There is a problem that stable running cannot be performed due to reduced performance.
[0004]
[Patent Document 1]
JP-A-5-213006 (FIG. 1)
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a high turning force at the time of turning and also improves a performance of absorbing shock and vibration from a road surface, thereby enabling a high-speed turning of a motorcycle. It is an object of the present invention to provide a tire for a motorcycle that enables stable running at the time.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention has been made, and its gist configuration and operation will be described below.
[0007]
The motorcycle tire according to claim 1, further comprising: a tread portion; respective sidewall portions that extend radially inward from a side portion of the tread portion; and a bead portion provided on an inner peripheral side of the sidewall portion. A carcass comprising at least one carcass ply having at least one carcass ply which is toroidally extended between bead cores disposed on each bead portion and has a side portion wound radially outward around the bead core, and a radius of the carcass In a motorcycle tire comprising a belt composed of one or more belt layers disposed on the outside in the direction,
At least one belt layer is composed of cords arranged substantially in parallel in the circumferential direction, and in a tire meridian section in a no-pressure state, a first arc-shaped portion convex inward in the radial direction, and a first arc-shaped portion. The second and third arc-shaped portions located outside and in the width direction of the width direction and smoothly or directly connected to the arc-shaped portion and respectively convex outward in the radial direction,
When the width direction position w of the center of the first arc-shaped portion is represented by the peripheral length along the belt layer from the width direction end of the belt layer on the same side as the arc-shaped portion, the outer periphery of the tread portion Assuming that the peripheral length along the contour is TW, w satisfies Expression (1).
0.09 <w / TW <0.36 (1)
[0008]
In the above, the term "non-internal pressure state" means, strictly, a state in which this tire has completed vulcanization in a vulcanization mold, and "in a meridional section, the belt layer or the carcass in the radial outside (inside ") Has an arc-shaped portion that is convex in the shape of a belt layer or the carcass has an arc portion having a center of curvature outside (inside) in the tire radial direction of the belt layer or the carcass. I do.
[0009]
According to the tire for a motorcycle of the present invention, at least one belt layer includes a second arc-shaped portion that is located outward in the width direction from the first arc-shaped portion and is convex outward in the radial direction. When vulcanized using a tire vulcanizing mold having a normal cavity shape, the tread thickness of the tread portion corresponding to the second arc-shaped portion can be locally made thinner than the conventional one. This increases the compression stiffness of the tread portion of this portion, and as a result, locally increases the contact pressure of the tread portion corresponding to the second arc-shaped portion, which comes into contact with the ground when turning, thereby increasing the turning force. Can be. Further, according to the configuration of the motorcycle tire, since the turning force improving means does not dispose the reinforcing member or increase the rigidity of the bent region of the sidewall portion, the turning force is improved. The ability to absorb shock and vibration from the road surface at the time can be improved.
[0010]
Further, if the (w / TW) is 0.09 or less, the center of the second arc-shaped portion of the belt layer is too close to the widthwise end, and the contact pressure improving effect at the time of turning cannot be expected. This effect could hardly be confirmed in a feeling test on a real vehicle. On the other hand, when the (w / TW) is 0.36 or more, the flexural rigidity of the entire tread portion increases, and as a result, the ability to absorb shocks and vibrations particularly during straight running decreases.
[0011]
In the tire for a motorcycle according to claim 2, in the tire meridian cross section in the state of no internal pressure, the carcass is formed such that an arc-shaped portion that is convex inward in the radial direction is the first arc-shaped portion of the belt layer. It is provided outside the center of the portion in the width direction.
[0012]
According to the motorcycle tire of the present invention, since the carcass has an arc-shaped portion that is convex inward in the radial direction in the state of no internal pressure, the carcass has a natural curve when the tire is filled with the standard internal pressure. As a result, the arc-shaped portion that is convex inward in the radial direction becomes convex outward in the radial direction, and as a result, the belt layer radially grows outward in the radial direction, so that the tread portion corresponding to this portion, that is, The outer contour of the part that touches the ground during turning is bulged, smoothing the ground during turning, and increasing the belt tension suppresses deformation of the belt due to lateral force during turning, improving steering stability during turning. Can be done.
[0013]
The motorcycle tire according to claim 3 is the tire according to claim 1 or 2, wherein, in a tire meridian cross-section, a belt layer and a carcass between a belt widthwise outside a center of the first arc-shaped portion of the belt layer. A rubber is provided between them.
[0014]
ADVANTAGE OF THE INVENTION According to the tire for motorcycles of this invention, by providing an intermediate | middle rubber | gum, the arc-shaped part which becomes convex in a radial direction inside can be easily formed in a belt layer or a carcass.
[0015]
According to a fourth aspect of the present invention, there is provided the motorcycle tire according to the third aspect, wherein the maximum thickness of the intermediate rubber is in a range of 0.5 to 4.0 mm.
[0016]
If the maximum thickness of the intermediate rubber is less than 0.5 mm, the effect of improving the contact pressure of the tread portion corresponding to the portion where the intermediate rubber is arranged cannot be expected, and the effect is also confirmed in a feeling test on an actual vehicle. I couldn't do that. On the other hand, if it exceeds 4.0 mm, the bending rigidity of this portion increases, and the ability to absorb shock and vibration during turning decreases.
[0017]
According to a fifth aspect of the present invention, there is provided the motorcycle tire according to the third or fourth aspect, wherein the hardness of the intermediate rubber is in a range of 50 to 90 in JIS-A hardness.
[0018]
If the rubber cord is less than 50, the difference in rigidity between the coating rubber covering the cord of the belt layer and the inter-rubber becomes too large, and there is a possibility that cracks are generated from these boundary surfaces. In addition, the flexural rigidity of the tread portion corresponding to the portion where the inter-rubber is arranged increases, and the ability to absorb shock and vibration during turning decreases.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a meridional sectional view showing the motorcycle tire 1 of the embodiment in a state where vulcanization has been completed in a vulcanizing mold, and FIG. 2 is a partially enlarged view thereof. The motorcycle tire 1 includes a tread portion 2, respective sidewall portions 3 connected to side portions of the tread portion 2 and extending inward in the radial direction, and a bead portion 4 provided on the inner peripheral side of the sidewall portion 3. A carcass 7 comprising a single carcass ply which is toroidally extended between bead cores 5 disposed on each bead portion 4 and has side portions wrapped around the bead core 5 radially outward; It comprises a belt 9 consisting of a single layer of belt 8 arranged radially outside of the carcass 7.
[0020]
The belt layer 8 is formed of cords arranged substantially parallel to the circumferential direction. Specifically, a single cord or a ribbon of a plurality of cords is spirally wound in the circumferential direction over substantially the entire width of the tread portion. It is formed by winding into a shape. As a material of the cord forming the belt layer 8, nylon fiber, aramid fiber, steel cord, or the like is used.
[0021]
In the meridional section, the belt layer 8 includes a first arc-shaped portion A1 protruding radially inward, a second arc-shaped portion A2 smoothly connected to the arc-shaped portion A1 and intersecting with the equatorial plane E, and the arc-shaped portion A1 as well. And has a third arc-shaped portion A3 including the width direction end K. The arc-shaped portions A2, A3 are convex outward in the radial direction, and the radii of curvature of the arc-shaped portions A1, A2, A3 are R1, R2, R3, respectively.
[0022]
Here, the width direction position w of the center P of the arc-shaped portion A1 represented by the peripheral length measured from the belt layer width direction end K along the belt layer 8 is the peripheral length along the outer contour line R of the tread portion. Is TW, the above expression (1) is satisfied.
[0023]
Further, the carcass 7 has an arc-shaped portion A4 having a radius of curvature convex inward in the radial direction of R4 at a portion outside the center P of the first arc-shaped portion A1 of the belt layer 8 in the width direction. A lens-like rubber 11 is disposed between the belt 9 and the carcass 7 on the outer side in the width direction from the center P of the first arc-shaped portion A1. The inter-rubber 11 extends over substantially the entire area from the belt width direction end K to the center P of the arc-shaped portion A1, and by arranging the inter-rubber 11, the second arc-shaped portion A3 of the belt layer 8 and The arc-shaped portion A4 of the carcass 7 can be easily formed. The hardness of the inter-rubber is in the range of 50 to 90 in JIS-A hardness, and its maximum thickness T is in the range of 0.5 to 4 mm.
[0024]
In the motorcycle tire 1 of the present embodiment, the carcass is made of one carcass ply, but it may be made of a plurality of carcass plies. May be replaced with a belt composed of a plurality of belt layers. When the belt is composed of a plurality of belt layers, it may be composed only of a belt layer composed of cords arranged substantially in parallel in the circumferential direction, or may be composed of a belt layer inclined with respect to the equatorial plane. May be combined. Furthermore, when the belt layer is combined with a belt layer inclined on the equatorial plane, the belt layer may cover almost the entire width of the tread portion, or may be a portion in which a central portion in the width direction is omitted. It may be.
[0025]
In this embodiment,. The first arc-shaped portion A1 and the second arc-shaped portion A2 or the third arc-shaped portion A3 of the belt layer are directly connected to each other, but are interposed therebetween through a linear portion or an arc-shaped portion having a different radius of curvature. May be connected.
[0026]
【Example】
Taking the motorcycle tire having the structure shown in FIG. 1 as an example, a motorcycle equipped with the tire of this example is run on an actual road surface, and a feeling test is performed. The comparison was made with a conventional motorcycle tire different from that of the embodiment only in that neither the first arc-shaped portion A1 of the belt layer nor the arc-shaped portion A4 of the carcass was present. Table 1 shows the specifications of the tested tires and the test results. In addition, three types of tires whose specifications are shown in Table 1 were evaluated as the tires of the examples. In addition, two types of tires of comparative examples whose specifications are shown in Table 1 were also tested.
[0027]
The motorcycle used in the test had a displacement of 900 cc, tire sizes of 120/70 ZR17M / C for the front wheels, 190/50 ZR17M / C for the rear wheels, and a filled tire internal pressure of 250 kpa for the front and rear wheels. The feeling test includes "turning stability" indicating whether stable turning can be performed and "handling" indicating performance such as absorptivity to input from a road surface, operational feeling during turning, and responsiveness. Sex "was evaluated. The “turning stability” is a sensitivity evaluation item representing the magnitude of the grip force and the turning force at the time of turning, and the “handling property” is a sensitivity evaluation item representing the degree of the absorption performance. These results were measured on a scale of 10 out of 10 based on the driver's response. Table 1 shows this score as an index with the conventional example being 100. Therefore, in Table 1, the larger the number, the better the performance.
[0028]
[Table 1]

[0029]
In Table 1, the width direction position of the point P is expressed by (w / TW), which is the width direction position w of the center of the arc-shaped portion of the belt layer 8 that protrudes radially inward, as described above. It is a number. As is clear from Table 1, even when the arc-shaped portion A1 protruding inward in the radial direction is not provided on the belt layer, or even when the arc-shaped portion A1 is provided, the position in the width direction is represented by Expression (1). If it is not within the range, the turning performance and the absorbing performance cannot be improved.
[0030]
【The invention's effect】
As is apparent from the above description, according to the present invention, the belt layer composed of cords arranged substantially in parallel to the circumferential direction has the arc-shaped portion A2, which is both radially outwardly convex in the tire meridian section. Since the arc-shaped portion A1 that is convex inward in the radial direction is disposed between A3, a high turning force at the time of turning can be secured, and the absorbing performance against impact and vibration from the road surface can be improved.
[Brief description of the drawings]
FIG. 1 is a meridional sectional view of a motorcycle tire according to the present invention.
FIG. 2 is a partially enlarged view of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Two-wheeled vehicle tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 7 Carcass 8 Belt layer 9 Belt 11 Intermediate rubber A1 to A3 Arc part of belt layer A4 Arc part of carcass P Arc part of belt layer A1 Center K Width end of belt layer

Claims (5)

A bead core comprising a tread portion, respective sidewall portions connected to the side portions of the tread portion and extending inward in the radial direction, and bead portions provided on the inner peripheral side of the sidewall portion, and disposed at each bead portion. A carcass comprising at least one carcass ply with a side portion wound radially outward around a bead core with a toroidal extension therebetween, and one or more belts disposed radially outside the carcass In a motorcycle tire having a layered belt,
At least one belt layer is composed of cords arranged substantially in parallel in the circumferential direction, and in a tire meridian section in a no-pressure state, a first arc-shaped portion convex inward in the radial direction, and a first arc-shaped portion. Are connected directly or indirectly to this arcuate portion located in the width direction outside and inside, and have second and third arcuate portions that are convex outward in the radial direction, respectively.
When the width direction position w of the center of the first arc-shaped portion is represented by the peripheral length along the belt layer from the width direction end of the belt layer on the same side as the arc-shaped portion, the outer periphery of the tread portion A tire for a motorcycle that satisfies the formula (1), where TW is the peripheral length along the contour line.
0.09 <w / TW <0.36 (1) 2. The motorcycle according to claim 1, wherein in a tire meridian cross section in a state of no internal pressure, the carcass has an arc-shaped portion that protrudes radially inward from a center of the first arc-shaped portion of the belt layer in a width direction outside. tire. The two-wheeled vehicle tire according to claim 1 or 2, wherein in a tire meridian section, an inter-rubber is provided between the carcass and a belt that is laterally outside the center of the first arc-shaped portion of the belt layer. The two-wheeled vehicle tire according to claim 3, wherein a maximum thickness of the intermediate rubber is in a range of 0.5 to 4.0 mm. 5. The motorcycle tire according to claim 3, wherein the hardness of the intermediate rubber is in a range of 50 to 90 in JIS-A hardness.

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